Characterization of the key odorants in milky aroma small-leaf yellow tea and their dynamic changes during processing...

The milky aroma is recognized as a distinctive olfactory characteristic in tea. Key aroma compounds and metabolic pathways in milky aroma small-leaf yellow tea (MSYT) were decoded by molecular sensory science approaches. A total of 59 volatile aroma compounds were characterized, including 25 aroma-active compounds (FD ≥ 64) and 22 with OAV ≥ 1. The aroma recombination test successfully reproduced the overall aroma profile of MSYT. Omission tests identified 18 key aroma-active compounds, with dihydro-5-pentyl-2(3H)-furanone and 2,3-octanedione being determined as critical contributors to the milky aroma. Lipid oxidation-derived γ-hydroxy fatty acids and 3-methylnonane-2,4-dione were speculated as precursors of these two compounds. Dry-heat chemistry action in the third yellowing stage accelerated their conversion, driving aroma transformation from floral and fruity to milky during the processing of MSYT. This study elucidates the key aroma-active compounds related to the milky note and their potential formation pathways, providing a theoretical reference for targeted process control.